Battle of Beltane
by Luxorien
Summary: When Agravaine makes his move, Merlin is ready. But in saving Camelot, he may lose his king. AU reveal!fic starting with "The Sword in the Stone." Posting as chapters are edited.
1. Warnings and Whispers

Arthur wasn't exactly surprised. Merlin _had_ seemed a bit...jolly. Even for Merlin. Perhaps his manservant should muck out horse stalls the next time there was a feast; if the boy collapsed at every major festival of the year, people would start to talk. More.

At least this time Merlin staggered a bit but didn't fall, avoiding the attention of the etiquette-conscious nobility. The only eyes his clumsiness drew were Gwaine's, the knight tracking him as he stumbled for the servants' corridor. Arthur excused himself casually, not wanting to miss out on the opportunity to berate Merlin for his indulgence. When they were hidden from the view of the court by the massive pillars of the great hall, he steadied Merlin gently.

"Started the revelry a bit early, did we?"

"Arthur."

He'd been about to make another witty (well, the wine made it seem witty) remark about servants who imbibe too freely, but his throat seized as though his voice had been plucked away by a hunting hawk. Merlin's eyes looked very blue and very wide, glittering in the wavering torchlight with a fey shine that the king found difficult to reconcile.

"They're coming. It's tonight."

"You're talking nonsense again, Merlin. Go sleep it off before you set someone's beard on fire." He tried to force an unconcerned imperiousness into the words. Somehow, they carried all the weight of a leaf before a thunderstorm.

"It was all for you, Arthur. Everything I ever did. I hope you know that."

All bravado fled, and he could only frown in sober confusion.

"I'm sorry."

And with that, Merlin was gone.

The baffled king stood there a moment and watched Merlin hurry down the hall and out of sight. It was typical Merlin, of course: get knackered, say something cryptic, show up next morning looking like you rolled out of a haystack. A _cheerful_ haystack.

He turned back to the feast, even started to shake his head and regain his seat at the head of the long table. But he looked at the gathered nobles, the bright light that illuminated the tables and left the walls in shadow. He listened to the waves of laughter rolling out between the clinks of goblets raised in fellowship.

 _They're coming._

Arthur turned his motion toward the table into a purposeful stride for the door. This garnered a bit more attention, but the varied conversations continued. As long as the wine kept flowing, Arthur's court would be just fine without him. A brisk gesture to one of the guards outside made the armed man fall into step behind him as he swept down several corridors and a colonnade, heading for the outer battlement. The guards on duty there covered their surprise well; if they thought Arthur's sudden appearance strange, it did not color their reports, which were unambiguously mundane.

He turned to look out over the city, scanning the darkened streets for signs that all was not as it should be. For several long moments, he saw only the torches of patrols and the celebratory bonfires in every quarter. The guards were right: everything looked as it should. But he couldn't shake the echo of Merlin's warning, and dread settled in his gut as he recalled other warnings his servant had offered, warnings which Arthur had ignored. He turned to the solider he'd brought with him.

"Find Lord Agravaine."

Before the man's footsteps had even faded, fires exploded in the lower town, licking through streets and across buildings with uncanny ferocity. No natural fire could burn so swift and hot, gnawing at the city like a living thing. It moved with a steady and obvious purpose, cutting off escape from the castle. In its fierce light, dark-armored troops could be seen approaching the walls that enclosed the courtyard. Arthur felt the cold grip of fear on his spine before a lifetime of training clamped down over it and began issuing orders.

 _They're coming._

Within the span of a few minutes, Arthur had raced from one end of the castle to the other, sending messengers scurrying in every direction as he went. Orders rippled down the chain of command like grains of sand in an hourglass, stirring the castle's defenses from slumber. To a man, his knights and servants responded with speed and courage, but he already knew it wasn't going to be enough. The enemy was already inside the walls. They might keep the citadel, but the _people_ were in the town.

Arthur's despair grew with every order he gave, because he knew that he had already lost. He had faced heavy odds before, but this...there didn't seem to be any point in it. Except that it was in his blood to fight, as long as he had breath. He simply did not know any other way to react. His heart quailed, but his mouth kept giving orders and his hands reached automatically for the crossbow his servants brought him.

The first catastrophic rumbling swept across the city just as Arthur was turning to descend from the battlements and marshal his knights. The very stones beneath his feet shook like a storm-tossed sea. It was hard not to believe that the citadel would be pulled down on top of their heads. Indeed, several men-at-arms dove to the ground in alarm. Arthur spared a moment to gaze searchingly in the direction of the tumult, but the night hid its source.

"Eyes forward!" he shouted to the cowering soldiers. He didn't pause to make sure his orders were obeyed but leapt down the steps three at a time.

He met Leon in the courtyard, the angry blaze of the burning city casting half of every face in a devilish light. "Sire, what about the lower town? Should we not attempt a defense?"

"The outer walls are lost. We'll be fighting in the streets. I want you and Gwaine with me. Our objective is to cover the retreat of the people into the citadel. Elyon will oversee the reinforcement of the inner wall."

Arthur watched the disbelief and horror flicker across his first knight's face like a shadow across the sun. It was quickly replaced by grim professionalism as he passed his orders on to his cohort. Gwaine and his men rolled in a few breaths later, but they needed no orders. As usual, Gwaine seemed to know Arthur's mind without the necessity of words, as least when it came to a fight. It was one of his most annoying habits.

There was no space for conversation once the battle was joined in earnest. Knights swept through the streets, citizens dashing past as swords rose up to meet the invaders. Archers softened the enemy line where they could, but the risk of hitting Camelot's citizens was high. It was tempting to push forward, but Arthur knew the initial momentum couldn't last. Fresh blades were flooding into the city, outnumbering Camelot's defenders at least two to one. He kept his men in place, ready to fall back once the stream of peasants and tradesmen thinned. The enemy had already cut them off from most of the city, but they could provide refuge for those closest to the citadel.

A second explosion shattered the night, knocking men from their feet even as they fought. Knights and invaders alike began coughing as a thick cloud of dust rolled over the city, blown by an easterly wind. Arthur sliced his way clear of the melee and leaned into that wind, watching as the tide of soldiers ebbed, at least from that flank.

He watched, and he wondered.

"Hold here. Sound the withdrawal when the people are safe."

"Yes, sire." The only sign of Leon's confusion was a furrowed brow. Arthur chose to ignore it, moving off down the streets alone, swiping at invaders as he passed. There were fewer and fewer of them as he moved closer to the source of the fine dust that was settled over this part of the city. In a few minutes, he arrived at what he had known, in the back of his mind, would be his destination all along: the entrance to the one of the recently constructed siege tunnels. It was the only explanation for the invaders' sudden appearance inside the walls of the city.

Arthur squinted in the dim light and tried to breathe as little of the dusty air as possible. It was clear that there would be no more soldiers pouring under the city's walls from here. The tunnel had collapsed, killing the men still passing under and spewing a fountain of debris out onto the tightly patrolled corridor that ran the length of the wall. The hidden steps that had led to the gated tunnel now disappeared under a pile of masonry.

Arthur thought then of the months spent laying out the plans for these tunnels, and the care taken to ensure their secrecy. And he thought of Merlin's insistence that they had been compromised. He saw bright blue eyes in flickering torchlight, and he heard again that whispered warning.

 _They're coming._

He didn't really think about it. He just ran, down the corridor to the next tunnel, almost losing his feet when a blast swept across the stones like a hundred heavy horse. He wasn't sure if it was relief or dread that welled up in him when he saw Merlin, winding among the bodies of invading soldiers as he made his way to the sharp-cut steps.

Arthur almost called out to him. Part of him believed that if he said Merlin's name, the fool would turn around and explain what was happening, and nothing would change. Instead, he watched silently as Merlin leaned into the tunnel. He watched as his most trusted servant uncovered a bizarre-looking sigil that had been etched into the stones of the tunnel, a sigil that Arthur had never laid eyes on, despite having overseen the construction of the tunnels himself. He heard the strange words that Merlin spoke, and he saw the burnished golden glow right before the tunnel collapsed, as efficiently as any sapper could have devised.

Arthur wasn't really conscious of walking out into the dust-choked alley. He almost didn't notice Merlin's turn at the sound of chain mail and booted feet. But he was aware of the great chasm opening between them, like the world falling away into nothing, and he could only think, _not Merlin. Not after everything._

He knew he was supposed to be doing something, but he could only stand there, his bare sword practically scraping the cobbles. Nothing in his entire life had made less sense than this. Perhaps he was going mad. Or perhaps it wasn't Merlin at all but a seeming, such as vengeful sorcerers had been known to cast. Perhaps Merlin was dead already.

Yet the expected hateful sneer didn't come. There was no tirade justifying the betrayal, no litany of Camelot's crimes against magic. That was when he knew it was Merlin: when he looked into his servant's eyes and saw not anger, but only a deep, immeasurable sorrow that gradually turned into resignation. When Merlin spoke, his voice shook with something that was not quite regret.

"Your sword is not Camelot's only defense."

He turned away before Arthur could make any answer, and began sprinting toward the next tunnel. When a small scouting party advanced from the other direction, he did not change course or pace, but simply kept running, as though expecting the invaders to part before him. And, borne on an invisible tempest of magic, they did.

Arthur stood there, staring after him, until he disappeared into the haze.


	2. Loyalties Lie

Gwaine couldn't help it. It wasn't that he was ignorant of the significance of what had just happened. It wasn't that he was unfeeling or didn't care that this was probably the worst day of Arthur and Merlin's lives. It was just that his tongue was like a second blade: handy for cutting, but shite for most else. He could not dispense wisdom as Merlin could, nor rally a soldier's courage like Arthur. A good gloat, though, _that_ was within his power.

"Ha! I've just won three gold crowns and a well-shod horse."

It was worth the three crowns to watch the startled king of Camelot whirl around, expecting an enemy, only to exhale a disappointed, long-suffering sigh when he recognized Gwaine.

"You were to cover the withdrawal into the citadel, Sir Gwaine," Arthur growled in a tone of voice reserved for the days when Arthur regretted bestowing that particular knighthood, which was most of them.

"I felt duty-bound to serve as your rearguard, sire. Haring off in the middle of an invasion can be a dangerous business. I didn't want to miss out. Er. On the chance to protect your royal backside."

Arthur blinked at him. "Why have you just won three gold crowns and a well-shod horse?"

"Why, Merlin's magic, of course. Percival and I have a wager."

In the blink of an eye, Gwaine found himself looking down the wrong end of the king's blade, the razor point of which was pressed to the hollow of his throat. "Treasonous words, Gwaine."

"Is it treason to engage in some friendly speculation after a tankard or...five?"

"If you knew-"

"I knew nothing." Schooling his expression to seriousness, he looked Arthur in the eye, knowing the king would see the truth of it. "I only suspected."

"The protection of this kingdom is not a game nor a joke-"

Fittingly, Arthur's tirade was cut short by another quaking rumble that shook the stones beneath their feet. Gwaine didn't feel the cut, only the thin trickle of blood that began dripping down his neck. He could have used this opportunity to roll away and raise his own blade, but for once he didn't feel like fighting. Some things were too important to cross swords over.

"It's no joke, sire," he agreed. "But be honest: if I'd accused Merlin of sorcery, you would have punched me in my face and sent me to the stocks."

The sword didn't tremble, but something in the king's eyes did. Gwaine could see the grief there, and the despairing wonderment of the betrayed. That was why Gwaine had stayed in Camelot when every instinct was screaming for him to leave: because in Uther's eyes there would have been only rage.

After a long moment, Arthur withdrew his sword. "It seems I can trust no one."

"Oh, that's where you're wrong, sire. Still, I'd wait till _after_ Merlin saves Camelot before you hang him." His statement was punctuated by another deafening explosion, the cries of knights and invaders cresting in response. Their clashing steel was moving closer, drifting through the dark and the dust.

Arthur didn't need to speak. Gwaine knew his mind before he acted, because the next stroke of the sword could always be seen in the eyes. They turned almost as one, and began jogging back to the main concentration of fighting.


	3. Eye of the Storm

All around him, men were dying. The air was clogged with blood and dust. The last tunnel's collapse reverberated through the city like a dragon's roar. And yet, the horizon of his thoughts remained unbroken. A great, hollow numbness was spreading outward from the memory of what had happened. Camelot was falling down around his ears, but all Merlin could see was the look on Arthur's face, as though the moment would go on forever.

He'd thought about it before, of course. He'd imagined telling Arthur a thousand times, in a thousand different ways. His dreams were full of daring hope. His nightmares always ended on an executioner's pyre. Over the years, he had constructed a multitude of arguments to explain himself, in the hopes that his king's wrath might be turned aside with words. None of those things occurred to him now. If Arthur had been in front of him, he wouldn't have been able to speak. All he could think of was the sound of booted feet on cobblestones, and the devastation unfolding as he turned.

He hadn't held out much hope of secrecy before, but now any pretense was gone. He stalked the streets of the city, using magic more liberally than he had in his entire life. Men died by the score, struck down in blasts of wind and tumbling stone. The first time he'd killed with magic, he'd thrown up afterward. Now he felt nothing.

Nothing at all.

With the tunnels collapsed, he turned his attention to the outside walls, where a great army was massed. Not enough for a siege, perhaps, but a significant force nonetheless. With most of the outer guard dead or surrounded, there was not much hope for a conventional defense of the outer walls. As he ascended the steps, he did not encounter a single soldier or knight. Only their mangled bodies and fallen weapons. Morgana's thugs had done their grisly work with precision and efficiency, leaving no one to raise the alarm.

Blood was pooling at the top of the stairs. He stepped clear of it and searched the walkways that ran from tower to tower. He found only death. And on the plains below, he could see torchlight glittering as the main force reacted to the collapse of the tunnels. They looked like they were rallying for an assault on the city.

Merlin thought of the townsfolk still trapped in their homes, laying low until the battle passed them by. It was impossible to tell how many had been able to flee to the citadel, but their number could not have been great. With the gates now undefended, the invaders would not need the use of the siege tunnels, and Camelot's defenders would be sorely pressed to win back the city. He conjured light and examined the crenelations for the marks he'd put there weeks ago.

It was funny, really, the way he had laid down spell after painstaking spell, knowing in his heart that he would be exposing himself, yet maintaining a sad little hope that his identity could remain unknown. As he glanced from the distant lights of the citadel to the approaching torchlight, he laughed. His voice sounded like broken glass, and then the rush of magic filled it. He had spent weeks laying dweomers all over the city. Now he spoke the words that would bring the enchanted stones to life.

It was an immense working. He did not realize how immense until he started pouring himself into it. He couldn't remember the last time a spell had taken so much so fast, like a dam bursting inside of him, power flooding out into the city. Tearing a building down didn't take nearly as much energy as bringing one to life. It felt as though a piece of him went with his magic, and he could sense the enchantment stirring all along the walls. It shivered to life, breathing with his breath, beating with his heart.

As Merlin sank to his knees, the stones of Camelot rose, flowing into the sinuous shapes of dragons: the crest of the royal house given lithic vitality. They erupted from the battlements, six great figures of stone that moved like living things. Stone wings arched over them because Merlin could not imagine a dragon without wings, but they were made of earth and bound to it, climbing down the ramparts and crawling toward the invading forces. The ground trembled under their stone claws, and the blue fire in their bellies illuminated them from within. They blazed across the darkened field, eclipsing the sea of torches borne by Morgana's soldiers. He prayed that her men would simply lose their heart for the fight.

Something spurred the invaders on. Perhaps they were enthralled, or commanded by captains as relentless as any Pendragon. Whatever the reason, they advanced, torches held high and battle lust thickening their screams. Merlin closed his eyes, but he could still the feel the tiny flickering souls that made up cohort after cohort. He could sense the life in them, misguided though they were. He knelt before the sheer drop of the parapet and shook.

The dragons paused in their advance, extending their stone wings and howling out their power in simultaneous mournful cries. "Just go," Merlin whispered futilely. "Just walk away."

The screaming lines of infantry continued to advance, closing in on Camelot's walls like the tide, as though they expected to simply bowl the dragons over with the sheer weight of their numbers. The fire lighting the creatures' scales intensified, turning a brilliant white-hot sapphire. Fanged maws opened on the approaching troops.

Merlin choked back a sob and released the flames.

The fire that roiled inside the stone dragons came rushing out in a devastating wave more ruinous than Kilgarrah's breath. It was instantaneous and devastating. The vanguard simply vanished, leaving only scorched earth to mark their passing. Further back, the fire reduced entire files to masses of charred bones. As the bodies piled up, the ranks finally broke, sending men fleeing in all directions. Most died before they could run very far, mangled legs bringing them to flailing halts. And when they fell, the superheated earth stilled their cries almost instantly.

The field was empty in a matter of minutes.

With a weary stagger, Merlin climbed to his feet, fingers scraping against stone. The wind that normally beat ceaselessly against the battlements was still. Banners hung limply from their posts. Nothing moved in that great, yawning emptiness. Nothing remained but ash and dust. He stared at it for a long moment, terrified by his own indifference. Where there should have been remorse, there was nothing but the cinders of his power, ready to be lit again in fury.

Slowly, the sounds of battle reached his ears. There were rivers of steel in the streets, pouring toward the castle. Rivers that he could stem without lifting a finger. The notion brought Arthur immediately to mind, covered in battlefield grime, betrayal pouring from him like blood. Less than a third of Morgana's army had made it through the tunnels before he'd collapsed them. Surely the castle barracks held enough knights to defend the citadel against such a force. With the invaders in disarray and separated from their fellows, the knights would likely be able to push them back and reclaim the lower town.

Unless, of course, Morgana had made it through.

Step by exhausted step, Merlin began making his way back through the hazy streets. He followed the clash of swords and the shouts of knights, winding between deserted buildings and lifeless bodies. He stopped every so often to close his eyes and listen for the whisper of magic, though in Morgana's case it was more likely to be a scream. But all he could feel was fire and ash and death and emptiness. And when he slipped under the shadow of the citadel, the dragons of Camelot thundered in his wake.

 **A/N:** _Usually don't do these, but just wanted to say thanks for the helpful comments on previous chapters._


	4. Between Two Fires

It should not have surprised him as much as it did. The presence of enemy soldiers within the city's walls spoke clearly enough of Agravaine's treachery, and it could not have been coincidence that in Camelot's darkest hour the man was nowhere to be found. Arthur had been subduing his own suspicions for too long, justifying his uncle's actions because he didn't want to believe that his strongest ally was actually working against him. In his heart, he knew. He should have known all along.

Yet it was still a shock to see him marching down the street at Morgana's side, unashamed of the company he kept. He didn't seem to care that Camelot's citizens were dying in the streets, or that a line of red-cloaked knights opposed his dark mistress. Like Morgana, he was empty of pity and fear, advancing relentlessly to the heart of the city.

"She'll fell us before we ever get close." Leon's voice, wary but unwavering, jolted Arthur from his grief. Indeed, the soldiers who didn't fall to Morgana's warriors were torn apart by her magic, a dark golden fire simmering in eyes that used to shine green in the sunlight.

"We'll flank her. I'll take front, Leon left, Percival right. Gwaine." He nodded at the ale-swilling git, not wanting to admit that he'd given him the rear because he was the best sword in Camelot and this needed to be perfect.

Then they were rushing into the iron-soaked haze of the front line, a pathetic barricade across a city street. They would have lost fewer men if they'd retreated to a more defensible position, but refugees were still streaming into the citadel behind them. Grandparents and children would be saved, though mothers would weep for their sons. So it went.

Camelot's only hope was in speed. They had to hit Morgana quickly, repeatedly and decisively. Let her unleash her magic on them one at a time, cloaking their final strike in the barrage so that she wouldn't see it coming until it was too late. Arthur swept his blade through broad, devastating strokes, tearing apart her mundane defenses as he prepared himself to face her punishing magic.

But it was Gwaine who moved too quickly to be stopped, throwing his king a helpless sort of grin as he charged Morgana, leaving Arthur with no choice but to switch their roles. As the long-haired knight threw himself forward, Arthur charged past the distracted witch, diving deep into the sea of southrons behind her.

In the flurry of battle, it is easy to lose sight of your goal, to drive at the thing in front of you and miss what approaches from behind. The knights had charged Morgana's army, mingling with the men that surrounded her until she couldn't possibly tell friend from foe. Her magic erupted anyway, hammering her own forces even as it struck down the knights. Arthur was thrown back with the rest, struggling to breathe as he lay on the cobbles, stunned. Morgana stood alone, raking her gaze over the piled bodies.

But she never reached Arthur. Somehow, Gwaine was up again, half his face sheathed in blood and his eyes alight. Arthur wanted to scream at him to wait, because he wasn't ready, couldn't find his feet, couldn't _breathe_. He forced his limbs up, moving toward Morgana while she was concentrating on what was in front of her. Arthur didn't see his uncle until it was too late.

Pendragon screams rent the night, filling the air with pain and rage and frustrated schemes. Agravaine had saved his queen from a mortal blow, but she had not escaped unscathed. Arthur had failed, and that was infinitely more painful than the rib-cracking blow his uncle had dealt him. Morgana spun, eyes blazing ,and yanked Arthur across the street, his armor throwing sparks off the stones. The world went white for a moment when he hit the makeshift barricade. It felt like his chest had been crushed and he couldn't think, still could not find his breath.

As he lay there, he noticed the ground rocking with great rhythmic tremors. They were hard to miss because each one sent waves of stabbing agony coursing through his battered body. He managed to open his eyes, and saw Morgana advancing, Agravaine and his bloody sword at her side. She was holding her ribs where he had slashed her, but she was smiling that horrible smile that meant madness and death at the hands of one he'd once loved.

"Oh, dear brother of mine."

When a great hulking shape rose behind her, its eyes glowing molten in the darkness, he thought she must have summoned some hell-beast to finish him off. But Morgana turned, her own eyes as wide as a startled doe's. She shouted a few words and thrust her hand out to drive it off. Fire lit up the night, and the creature was illuminated, its stone scales and spear-like teeth untouched by the flames. Morgana began stumbling to the side, and the huge sculpted head swiveled to follow her with a motion too sinuous for such a cumbersome creature.

Arthur would have flinched, but his aching muscles would not respond to his fear as an enormous clawed foot passed over him – and by all the gods, it was _solid stone_ , moving like a living thing. The bulk of the creature straddled the fallen king, the long neck arching across the street. It was a fourth the size of a real dragon, but there was azure fire in its belly that seared the night air.

It was difficult to reconcile such an obviously magical creature with the skinny fool who served him breakfast every morning, but Arthur knew it was Merlin's doing. He'd seen only two sorcerers this day, and Morgana obviously didn't summon the thing. Her lips drew together in a tight line of terror as she backed away from the dragon.

Morgana tried another spell, and another after that. The words of the old religion poured from her in a torrent, chased by fear and desperation. Lightning crashed and the earth shook. Chips of stone rained down on the cobblestones, but the creature did not appear to suffer any serious damage. Agravaine rushed to Morgana's side, brandishing his useless sword. And then the dragon breathed.

The light and heat were too intense for the actual strike to be seen, but when Arthur blinked the spots from his vision, he could see Morgana crouched against the wall of a neighboring building, the stone around her literally red-hot, and the glow of sorcery fading from her panicked eyes. Agravaine was nowhere to be seen. There were more thudding impacts from down the street, as two more of the incredible living statues approached. The first one was opening its maw again, fire kindling inside like a fallen star, when Morgana screamed out a complicated incantation. A great wind gathered around her and she disappeared into the swirling tempest before the flames hit the cobbles.

For a few moments, silence blanketed the street, broken only by the faint hissing of stones superheated in the false dragon's breath. Arthur began levering himself to his feet, biting back the growling cry that threatened to escape him when his ribs protested the movement. He slid out from under the stone beast, which was just standing there, staring at the place where Morgana had been a few heartbeats ago. Arthur let the barricade take his weight and just breathed into the quiet, trying to collect his thoughts. He watched warily as the stone dragon moved once more, joining its fellows further down the street. They seemed to be taking up defensive positions, treading on a blanket of Morgana's followers as they went.

Arthur looked at the ground around him, searching the fallen for signs of life. Leon and Percival groaned when he prodded them, rising slowly, eyes glazed but limbs sound. None of their enemies seemed to have survived. Every one of the invaders had either been defeated in battle or crushed by the stone behemoths. From the other quarters of the city, he could hear screams and roars. Fire was running rampant, fed by the magic employed on both sides.

The king barked a few hoarse orders to the recovering men. They needed reports from the other cohorts so that men could be redistributed and battlements reinforced. It looked like the last of the refugees had made it inside while Morgana had been occupied, and now a decision would have to be made: withdraw to the citadel or push out toward the city walls, where hundreds of people were no doubt trapped behind the enemy lines. He would not have entertained the latter option an hour ago, but with the invading force seemingly broken, not just survival but victory seemed possible.

He was thinking about how odd a thought that was: to see sorcery countered with sorcery, when he noticed one body that was not moving, Camelot's colors lying over the still form. Percival, who had been pulling the other knights to their feet, noticed Gwaine at the same time Arthur did, but the king moved much more slowly.

"Does he live?" Arthur asked as he approached. Percival was putting a huge, grimy hand to Gwaine's throat. His fingers came away sticky with blood.

"There is breath in him yet, but it is weak."

Arthur was surprised at the strength of his despair. He'd thought that nothing could make this hellish night any worse, but the thought of losing Gwaine suddenly seemed too much to bear. He'd lost so many men, most of them loyal subjects that had served since Uther's reign, and none of whom had been keeping evidence of treason from their king. He didn't even particularly _like_ Gwaine, for blood's sake.

 _That smile as he charged, too defiant to be an apology._

He tried to assess the man's injuries, but he had only the skill to cause wounds, not heal them. He was about to send someone for Gaius, when Merlin limped out of the shadows, haggard and dusty but remarkably clean of blood, considering what he had...done. Arthur raised his blade and spent a moment wondering why his knights were so slow to follow suit. Then he remembered that the only knight who'd witnessed Merlin's exploits was unconscious. Out of the corner of his eye, he saw Leon and Percival looking from Arthur to Merlin warily, hands drifting to hilts with a hesitance that suggested they weren't entirely sure whose side they were on.

Merlin didn't answer Arthur's promise of violence. He just said, "I'll tend him." For the second time, the king found his blade sinking to the ground. But Merlin wasn't waiting for permission, moving even as he spoke and kneeling gingerly next to Gwaine. Arthur searched for words, but could find none. The accusations and demands that came to mind were shattered by the shadows under his friend's eyes, and the gentle fingers he used to feel for life and breath.

He recognized the look. Arthur had seen it before: on the battlefield and in the physician's quarters. It was a tightening of the mouth, a shuttering of the eyes. It was the face of a man preparing to dispense grim tidings. But Merlin didn't turn to give a diagnosis. He just knelt there, and a fierce denial settled slowly over his expression. His eyes never left Gwaine's face, and as the foreign words began falling from his servant's tongue, Arthur couldn't think of sorcery. Sorcery was hate and death and hurt. But Merlin's actions recalled only glasses raised in fellowship, and swords bloodied in the same battles.

Gwaine didn't wake, but he gasped like a drowning man, and his next breaths came strong and steady. Merlin swayed, and would have fallen if Percival had not supported him with one thick arm. Leon's sword was half out of his scabbard before he looked to Arthur, confusion and alarm warring for precedence on his face. Arthur knew that if he ordered it, Leon would execute Merlin on the spot. By the looks of things, he would have to go through Percival, but he would do it. Arthur felt the eyes of his subjects on him, waiting for his decision. All but Merlin, who had closed his in weariness.

 _I want to forget what I saw,_ he thought. _I want this to have never happened._ What he said was, "Take them to Gaius. We must secure the city. Sir Leon, keep watch over Merlin. He is not to leave the citadel."

It was strange, but sometimes he found himself waiting for his father to give the order. With every decision, even the most mundane, there was a part of him whispering that he would never be the king his father was, that he didn't have the _strength._ But Leon nodded briskly and set to his task. The other knights followed suit, securing the street and taking positions around their king.

Percival, after a strangely unreadable glance at Arthur, hoisted Gwaine onto his shoulder and made for the castle. Arthur tried not to look at Merlin as the boy stumbled along beside Leon, tried not to see the downcast eyes and hunched shoulders. A piercing combination of rage and confusion threatened to sweep away his resolve, but he had a kingdom to care for and a city to defend. The time for judgment would be later, when the tumult of battle had subsided. He turned back to the smoke-filled streets and collapsing buildings and tried not to see blue eyes fading to gold.


	5. Walls of Stone and Sorcery

Gwaine opened his eyes, and realized that nothing hurt. This was confusing, as his last memory was of Morgana screaming her rage into magic. He knew he wasn't dead because there was a distinct lack of mead and singing. Something inexplicable had happened.

"Where's Merlin?" His voice was rough, as it always was when he first awoke, and he wished he had some ale to blame it on. He wished he had some ale, period. He hauled himself into a sitting position and cast about for something to orient himself.

He was in the banquet hall that became a hospital every time Camelot was invaded (which apparently was every summer). There was no one nearby to answer his question: only cots occupied by incoherent men-at-arms. He could see Gaius binding a wound near the entrance, and an army of servants scurrying about with bandages and blankets. The air was filled with orders and reports, the complaints of the injured and the groans of the dying. He didn't see anyone who might be able to tell him what had happened, so he hopped to his feet and began making his way to the old physician's side. Gaius was a clever fellow – he would know what was going on.

The old man looked up as Gwaine approached, and his face had that closed, professional expression that meant bad news. In Gwaine's opinion, Gaius was the best liar in Camelot, and he always trod warily around him, concerned that his own half-truths might spontaneously come to light. That Gaius disapproved strongly of his drinking helped not at all.

"Where's Merlin?" He figured finding his best friend would be the quickest path to answers that didn't involve disapproving frowns. He was somewhat surprised by the grief that shadowed Gaius's face at the mention of his boy. A cold pit formed in Gwaine's stomach, and his hand ached for a sword.

"In the cells."

"The _cells_."

"His majesty sent word for you to report to him when I declare you fit."

"The _cells_."

Gaius picked up a clean bandage and began winding it around the arm of a soldier who was carefully pretending to be deaf. "I examined you while you were sleeping and it's my opinion that you're sound, at least physically." A raised eyebrow and a nod toward the long dining table that had been pushed against one wall. "Your sword is over there."

"What happened to Merlin?"

Gaius didn't answer right away. He finished the dressing and sent the soldier off, wiping his hands on a clean cloth. There were still minor wounds to be treated, but he ignored the expectant eyes, drawing Gwaine into a small alcove where the sound of their voices would sink discreetly into the tapestries.

"He's suffering from extreme fatigue, but with a few days' rest, he should be fine."

"A few days' rest in the _cells_?"

"The king has asked that he be held until the city is secure. I assume there will be a trial."

"What's he supposed to have done?" Gwaine knew the answer, but he'd thought Arthur would handle this quietly.

For the first time, Gaius' facade faltered, just slightly. There was a barely suppressed tremble in the normally steady voice. "He used...magic. In the presence of the king, and about a dozen knights."

"No..." Gwaine tried to scoff, but it felt unnatural and forced. It had been only Arthur and himself. No one else had seen. No one else would have to know.

"You were seriously injured in the fight against Morgana," Gaius explained gently, as though talking to a skittish horse. "Do you remember?"

"I remember the battle, but if there was a victory party afterward, I must have had ten too many tankards."

"You were on the brink of death. By all reports, I could not have saved you."

The realization settled over him then like a second skin. He remembered the pain of Morgana's magic, and the blood that had dripped in his eyes. He had watched her eyes burning gold as he raised his sword one last time, knowing he wouldn't survive another blast, but knowing also that Arthur would live, the bastard. He raised one hand to his temple, to feel for the gash that had been there, but there was nothing. He had no injuries to speak of, despite being covered in blood-spattered, dented armor.

"No..." Gwaine felt all the air rush out of him. For a moment, he couldn't find the words. Then anger swept away the shock. "Arthur has condemned him for an act of mercy?"

"No sentence has been passed."

"Not yet, you mean." Gaius just looked at him helplessly. "Well. I'm not going to stand idle while he repays Merlin's service with a pyre."

"Gwaine. In this, you must obey your king."

The depth of his defiance surprised even him, and he found himself spitting his words with all the venom of war widow's son. "If he has Merlin executed for saving my life, he'll no longer _be_ my king."


	6. The Taste of Darkness

Merlin slept, but fitfully.

Exhaustion carried him deep into slumber, but there was fire and death even in the sanctuary of his mind. Magic surged in his thoughts, a comforting wave of power that made it possible to ignore the consequences of his actions, at least for a little while. But the smell of burned flesh swept in soon enough, driving his sanity before it.

It seemed he walked under a storm-filled sky, struggling to cross an endless field of melted corpses barely recognizable as having once been human beings. The devastation stretched as far as he could see, the darkness of the deed mingling with the black sky. There were no stars nor sun to guide his path, but he trudged along anyway, carrying only a desperate hope that there must be an end – even to this.

After a time, he found himself standing in a throne room, its roof ripped away in huge, jagged chunks. On the throne was another skeleton, its head encircled by a tarnished crown. There was a cold wind blowing, carrying the stench of an open grave, yet he could not find his breath. He stared at the skeletal king, seeing the features it had worn in life, though nothing of the man he had been was left on this mutilated corpse.

 _I did this,_ he thought, though he could not remember the deed. He recognized the taste of his own power, the mark of that horrible devotion that made him capable of anything, of the worst things. It was in the air, weighting his tongue with the taste of ash and magic. He had destroyed what he had sought to protect.

What little light there had been suddenly winked out, and in the darkness, he could feel _her_ magic rolling over and through him, a great summoning that swept over the city, engulfing it in madness and despair. He tried to push it away, but what was the point? He was defending a city of the dead. They were squabbling over empty rubble and dust. It was all gone, blown away in the gale of their secret war...

He came awake all at once, with a gasp and a lurching movement away from the shadows of the dream. Someone was arguing, and he squinted in the torchlight as he rolled into a sitting position on the meager pile of dirty straw that was his cell's only furnishing. After a few moments, he could discern the outlines of two knights beyond the iron bars, facing each other like enemies on the battlefield. Merlin's heart leapt to see Gwaine hale and alert, but the fire in his friend's eyes bespoke trouble.

"-but I will not."

"It is not our place to question the king. The boy flaunted the law of the land. We all saw it." There was reluctance in Leon's eyes, but he nevertheless met Gwaine's anger with his own resolve. He was the kind of man who would do his sworn duty, no matter how distasteful he found it.

"You call this justice? To punish a man for acting with honor? To repay his service by treating him as a criminal?"

"He has broken the law!"

"The law is bollocks!"

"Stop," Merlin pleaded softly, knowing he would not be heard over the shouting but not trusting his voice, still thick with shadows. The two knights kept right on arguing, their hands tightening on hilts. He saw the imminence of violence in their eyes before they ever drew their swords, and his next attempt came out in a roar.

" _Stop!_ " Despite his weariness, power surged through him with the same strength as always, a rushing river that ran through the bones of the earth and the pillars of the sky. For a moment, he forgot why he had called it forth, reveling in that intricate connectedness which swept away the dark memories like dawn chasing the night.

Gwaine and Leon skidded across the floor in opposite directions, propelled gently but firmly against the walls on either side of the corridor that led to the cells. He held them there, pinned like kittens, until the fight drained out of them. Gwaine just looked annoyed, but Leon...Merlin winced inwardly when he saw the confusion and fear on the face of the man he'd considered a friend. He released them slowly and sat back against the clammy stone of the wall.

"It is Arthur's decision," he reminded them.

"Arthur's a beef-witted git." Leon recovered from his shock enough to glare angrily at Gwaine, but he made no move to silence him.

"He's angry. He has every right to be. He'll come round." Even as he said it, Merlin didn't believe. It was hard to, when thoughts of Arthur called to mind only the deep betrayal in his king's eyes. He'd always thought that it would be a relief when his secret was finally out in the open, had even entertained hopes that he wouldn't be summarily executed. He hadn't counted on the crushing guilt he felt at having so devastated Arthur. His good intentions and his ultimate loyalty paled in the face of the simple fact that he had lied, for so long and about so many things.

And given the things he was capable of – _burnt bodies of the dead stretching in every direction –_ who could blame Arthur for wanting to lock him up?

Gwaine said something then, but Merlin didn't hear it. The darkness was rising again, but not from his dreams. Somewhere, Morgana was casting a powerful, intricate spell, and the reverberations beat against the fabric of the world like breaking waves. It was changing the very air he breathed.

He thought he heard distant shouting, and the sound of iron banging against iron, but the magic was all he could see, and it was a blackness that would rise up to envelop the city. He'd never felt anything so powerful, and so deeply hungry for death. When the first tendrils of it crossed the wards he had placed on the outer walls, he felt it like a physical blow, and cried out with the icy pain of it.

The stone guardians he had brought to life were still roaming the city, picking off the few remaining invaders. They were born of Merlin's magic, and he reached out through that connection, directing them to a new task. They weaved through the shops and houses, making for the outer walls that had birthed them. Merlin could see through their eyes the knights pushing forward to reclaim the city, and he nearly despaired, driving the monolithic guardians faster and further, desperate to reach the gates before it was too late.

He didn't know what dark power Morgana had set against the city, but he thought of a spell that might repel it, at least for a time, if he could push enough of his waning strength into it. He paused for the barest breath to determine how the casting should be performed before he began incanting, pouring magic through his veins like fire.

He couldn't even tell if he'd been successful; when the last rushing wave of power left him, he lost contact. His magic had touched the dark sorcery that approached the city – that he knew. The crushing blackness of it had drawn a shadow around his mind, and he was conscious of little else. The only image that managed to make it through the fog was of Arthur.

 _Withdraw_ , he thought fiercely. _For god's sake, Arthur, run!_


	7. The Fires of Camelot

After the wounded (and arrested) were taken behind the walls, the soldiers of Camelot turned their attention to the city streets, where pockets of invaders were being steadily driven back or crushed. Arthur climbed the central guard tower to get a look at the areas his messengers had not reported on, and could not stop his jaw from sinking. There were still fires in every quarter, burning with the intensity of celebrations turned to bloodbaths, but there were no more red cloaks surrounded by hostile blades. Camelot's forces (if the inexplicable living statues could be considered part of the city's defense) had reclaimed most of the thoroughfares, replacing the roar of conflict with the silence of the dead.

He had just managed to reconcile himself to their impossible victory when Tollers returned, panting his messages and standing straight-backed for his next orders. The boy was lithe and swift, a squire under Sir Brastias' tutelage, but Arthur borrowed him whenever he needed a reliable set of eyes and a quick pair of feet.

"No word of the outer wall?"

"No, sire. The invaders have faltered, but Sirs Brastias and Bors await your orders to push past the...dragons." There was a light in the boy's eyes, a wonderment that Arthur almost wished he felt. For a moment, he considered asking Tollers how _he_ would handle a ridiculous servant who practiced magic under the nose of the king. He reminded himself that it was not Merlin standing before him. And he reminded himself why.

"I need eyes outside the walls. Tell me what lies on the common, as quickly as you can."

The boy's bow was respectful but brief, and Arthur knew he would complete the task without delay. The king turned as the sound of the squire's small boots beat a galloping rhythm down the steps. He hoped his scout would live to make his report. As he looked out over the hypnotizing flames, their light occasionally eclipsed by roaring, hulking shadows, he thought of Tollers sprinting across the battlefield his home had become. And he thought of Merlin, huddled in the citadel with the rest of the refugees.

Father would have executed him. Arthur tried to imagine beheading someone who could bring stone to life or liquify it. He tried to imagine killing the person who poured his wine at dinner. He couldn't fathom it, any more than he could fathom Morgana. The world was going mad, and Arthur thought he might go with it.

The word, when it finally came, was shocking.

" _How_ many dead?"

"All of them, sire." The boy's eyes were wide with fright and awe. "It's a charnal house. The smell is...unimaginable. I had to stop and wind a cloth about my face. Their entire army's been destroyed in dragon fire."

As a boy, Arthur was told a story of a king who did something so terrible that in his madness and shame he pried his own eyes from their sockets. It was a story the young prince had largely ignored, because he could not imagine seeing something so horrible that he would pierce his own flesh to rid himself of the memory. Now, standing in the middle of a burning Camelot and trying to imagine _Merlin_ killing thousands of men without lifting a finger, he thought he understood.

But he still had a city to protect, a country to rule. He could not afford to let the spreading waves of shock and disillusionment drown him. He forced himself to think in numbers, to picture the city from above. They had enough swords to take back Camelot tonight. That magic had made their victory possible was irrelevant. There was only one course he could in good conscience follow.

Arthur thanked the boy for his service and sent him to his master with the same orders that were about to be passed all down the line: press forward, secure the outer walls. He would have to dispatch a few cohorts to quench the fires that still raged through the city. Walking briskly down the latest barricade, he found Sir Percival, and took counsel with him, while swords sang in the streets around them. The tall knight had always been quiet, but now Arthur sensed a new hesitancy in his demeanor.

"What about the dragons, sire?"

"They don't seem to be attacking Camelot's colors. Leave them be." _As though we have a choice_ , he didn't say.

Percival nodded dutifully and moved off to convey the orders and lead the southwestern advance. Arthur jogged to the other end of the barricade, his ribs protesting with every step. Camelot's men-at-arms were fighting a pocket of invaders that filled the street, shoulder to shoulder from one building to another. Though their numbers were small, they'd used their position to effectively multiply their force, stymying the defenders as they tried to press forward. As Arthur snapped his sword to readiness, he saw one of the stone creatures begin stalking slowly down the street. Its tremendous jaws opened, and he thought it would let loose its fire at the invaders' rearguard, killing friend and foe alike.

But the dragon withheld its breath, and when it reached the knot of mercenaries, it slammed a clawed foot down, shaking the earth and dismembering Morgana's men. The movement was repeated with talon and teeth until the invaders were decimated. Arthur's forces made quick work of the remaining men, leaving only bloody cobblestones between them and the monster.

Arthur brought his sword to bear on the dragon, heedless of his own orders. With the thing so near, he could not help but ready his blade. But instead of attacking, the dragon bowed its long neck until the massive head was almost touching the ground. He stood there a moment, adjusting his grip on his sword and panting with the exertion of battle. But the dragon didn't move. Heart still thundering, he finally relaxed his aggressive stance and just stood there, bewildered.

For one vertiginous moment, Arthur imagined accepting Merlin's aid, thought what it would feel like to fight magic with magic, to take down Morgana's armies with a sorcerer at his side, no longer cowering in the dark like a child but striking back in kind.

 _How many dead?_

 _All of them, sire._

"Forward," he ordered curtly, and strode past the dragon with all the confidence of his office. Knights and men-at-arms followed, stealing glances at the dim flames licking the creature's bloody fangs. He could not escape the feeling of something changing his men, sweeping through them like a wave. It was in their eyes, their voices, the set of their shoulders as they raised their blades. Fear and confusion were giving way to...hope.

Arthur wished just one of them had argued.

He was spared the roiling crush of his thoughts by an ambush in the market square. The streets had been too quiet and now he saw why, as dozens of men leapt from the shadows of the deserted stalls. Arthur had to admire the move; it displayed a courage bordering on stupidity, but if he were trapped inside an city he had just invaded, he would probably do something similar.

There were a hundred soldiers behind him, but in the close quarters of the market, it might as well have been ten. Time was on Camelot's side, though. Their numbers would be replaced, where the pocket of isolated invaders would slowly be whittled away. It was a situation that urged caution, but Arthur found himself restless with the urge to push forward, to reach the outer walls immediately.

The king restrained himself, but his sword strokes became swift and almost reckless. He opened up a space wide enough for three knights, and had to pause while the battle caught up him. Because he was standing there, his bloodied sword at his side, he was the first to see the dragons.

In the rush of battle, he hadn't noticed the way the earth was trembling, but now he could feel the impacts as the creatures scrambled for the outer wall like enormous cats chasing mice. Their tails lashed through the air, whistling as they stirred the smoke-laden air. Arthur watched their progress in between blade strokes, hesitating in his rush forward. A few of his knights slowed also, watching with wonder in their eyes as the dragons leapt atop the outer walls.

Beyond the fires of Camelot, the stars had disappeared from the sky, swallowed by an unnatural blackness that pulled at the eye with a dizzying emptiness. The city's inexplicable stone guardians were bright spots of flame over the abyss. As one, they dug into the battlements and opened their jaws.

The blast shook the city. A hot wind blew back through the streets, and sapphire light cascaded from the outer walls, igniting the sky. The streets were illuminated, and the darkness halted at the gates. Knight and mercenary alike lowered their swords and stared upward, faces aglow with reflected sorcery. Crazily, Arthur thought he could hear Merlin crying out as though from a great distance, telling him to flee. It was an exhortation that matched his instincts perfectly.

"To me!" he cried, and began organizing a withdrawal. He sent his men sprinting down the streets, calling for the people of Camelot to retreat to the citadel. Most of the population had already made it past the gate, but there were some who had barricaded their doors rather than risk fleeing through enemy lines. And then there were the old, the sick, the stubborn. Some of these needed only a swift order from their king, or a strong arm to lean upon.

Red cloaks swirled through the streets, berating some and assisting others. Arthur himself lent a shoulder to an old woman who trembled as she hobbled toward safety. Some quick-thinking merchant had tossed his goods in the street and begun loading his cart with the infirm and elderly. Arthur turned toward it immediately, and helped the woman clamber onto the rough planks. She began stammering her thanks, but her voice faltered after the first syllable, either from exhaustion or because she noticed whose arm she'd been leaning upon. The king put a gentle, bloodstained hand to her shoulder and turned away to check the progress of the evacuation. Percival's cohort brought up the rear, sweeping the stragglers before them. Empty streets stretched beyond, bathed in the fey azure light that was still pouring over the city. Arthur moved through the streaming mass of people, urging on any who seemed inclined to linger.

It took several hours to collect all those who had been left behind and tuck them safely behind the gates of the castle. The portcullis had barely slammed shut when the dragon flames faltered, and the darkness rolled over the city like a yawning wave. For one terrifying instant, it seemed as though the sinister magic would engulf the citadel as well, but it halted as though fetching up against an invisible fortification. It hemmed in so close that the soldiers on the castle's outer battlements could have reached out and touched the eerie barrier, had they dared. In the courtyard, a shocked silence paralyzed the masses of townsfolk as they watched their homes and livelihoods disappear.

It was a good time for a speech. If he could put a name to the darkness, it would lose the greater part of its terror. Arthur ascended the steps two at a time, even drew an aching breath as he crested the top. But when he looked out over that sea of desperate, soot-stained faces, the words wouldn't come. He was a warrior, not an orator. There was a painful emptiness in his chest that had nothing to do with injury.

Yet as he stood there, crimson sweat dripping from battered armor, his leaden sword half-raised in anticipation, he could feel the character of the silence change. An enormous fellow in a blacksmith's apron let out a bellow, and hundreds of voices took up the defiant cry. It was a prayer and a promise, a trust that both humbled and elevated him. Arthur held his head level and offered a single unshaken salute. The people roared in response.

Their shouts followed him down into the dungeons.


	8. Illumination

Arthur didn't see Gwaine at first; the belligerent knight was actually standing inside Merlin's cell, arms crossed and feet planted. Leon had taken up a position just outside the open door, directing his stoic frown at the far wall. When his king approached, he smoothed his features and gave a short bow.

"Sire."

"I'd like a few minutes with the prisoner."

"Yes, sire." Leon gave Gwaine a disapproving glance, but slipped out obediently. When he'd gone, Arthur stepped up to the bars, moving gingerly as his armor dug painfully into his chest. Gwaine shifted his weight casually, but to a practiced eye (and Arthur's was _very_ practiced) the move was more threatening than a drawn sword.

"I'll not harm him, Gwaine. You have my word."

Gwaine opened his mouth, then closed it again, as he appeared to process Arthur's weary words. He eyed his king suspiciously for a moment. "He saved my life. Is that a crime in your kingdom?"

"You know it is not."

"But you still threw him in a cell."

"I'd like to speak with him. Alone."

"He's not..." And just like that, the hostility faded to fraternal concern. "I haven't been able to rouse him."

Arthur looked at Merlin lying on the meager straw, his skin pale and sweat-slick, his eyes moving frantically under closed lids. He thought of the workings of magic he had seen in the city, and he realized that he was neither surprised nor discouraged. "I don't think he's as insensible as he appears. Give me a few moments. If Merlin is harmed, I will submit myself to your judgment."

Gwaine looked both mollified and sheepish at that. He started to say something, but faltered as though searching for words. Arthur couldn't help a slight smile at that: the garrulous Gwaine rendered speechless. It faded as he considered for the first time the value of Gwaine's loyalty. Arthur had been taught to obey his king in all things, but now that the tables were turned, he was beginning to realize that he needed men like Gwaine as much as he needed men like Leon.

Arthur clapped Gwaine's shoulder and stepped past him, already thinking about everything he couldn't say to the man who had, in the span of a few hours, saved Camelot and upended her laws. "I'll be in the corridor...sharpening my sword," Gwaine called as his footsteps faded. And then it was just Merlin and Arthur, as it always was and would be: the two of them shoulder-to-shoulder against the world.

It was so familiar and so wrong. The half-formed words he'd turned over in his mind crumbled and he just stood there, watching Merlin's slow, painful breaths. Despite his assurances to Gwaine, he wondered if Merlin could even hear him. How long would his defense of Camelot hold? Was he simply delaying the inevitable?

But that wasn't Merlin. He was always irrepressible. He always made hope fly when her wings had been burnt to ashes. The illusion was shattered somewhat by the knowledge that he'd always had magic in his pocket to turn things his way, but it couldn't have been just that. That power, Arthur realized with a dawning wonder, could not have changed Merlin. He was defiance, with or without means for fighting back.

The king drew his blade and placed its point gently against the tight-fitted stones of the cell floor. Mailed fist clenched tightly around the hilt, he took a knee and whispered his words through shaking lips.

"This field belongs to you, Merlin. I do not know the manner of its unfolding. But if my sword can aid you, then it is yours."

At first, he didn't think he would get a response (how could he?), but as despair tightened his grip on his useless weapon, faint threads of light began to twine themselves around Merlin's arm, ghostly veins of blue and silver. They slid into his slack palm like rivers flowing into the sea, pooling and coalescing into a blue-white sphere that let off a pale, steady glow.

In one heart-stopping instant, Arthur was pulled back into the memory of a dark cave, and a quest that almost ended in the loneliest of defeats. He recalled the trembling in his fingertips as he clung to the narrow ledge, his booted feet swinging out over a fathomless abyss, his eyes blind to the approaching monsters. He remembered the sudden sorcerous light that guided him out of the blackness, illuminating a path first for his sword and then for his limbs as he clawed his way out of the earth.

That same light now curled about Merlin's fingers, rising up and escaping through the tiny barred openings that ventilated the dungeons. Though it quickly passed out of sight, Arthur knew instinctively where it was headed, and with a swift thrust of his bent knee, he was sprinting out of the cell and down the corridor, heedless of the calls of his knights.

He reached the courtyard in minutes and found the ethereal globe waiting for him at the outer gate. Refugees and soldiers had scattered from the strange magic, leaving an empty semicircle around the entrance to the citadel. Whispers were spreading like fire, some frightened, others entranced. Knights and men-at-arms, obviously unsure how to handle the strange occurrence, looked to their king in obvious relief.

"Open the portcullis!" Arthur shouted, slowing his pace as he approached the boundary between light and dark. The heavy gate could hardly be seen against the backdrop of impenetrable darkness, but it was clear where Merlin was leading him. His suspicions were confirmed when the globe edged forward and the darkness seemed to retreat from its advance.

Faces that had turned to Arthur for guidance now clouded with confusion at the strange order. "Now!" Arthur bellowed, chafing at the delay. White-faced guards began turning the winch, just as Leon and Gwaine came to a pounding halt behind him.

"Sire! This is madness!"

"Somehow, I don't think the portcullis is keeping anything out." Gwaine glanced pointedly at the skies above, where the darkness stretched upwards but did not cross above the citadel.

"We can't fight this from behind the walls," Arthur explained, feeling a clarity and certainty that had been entirely absent since the warning bells first began to ring. For the first time, he _knew_ he was doing the right thing. "We must go on the offensive, before our fortifications give out." _Before Merlin gives out_ , he didn't say.

"Hell, you know I'm in," Gwaine said, lifting a sword and a smile. Leon was more hesitant, his face stony. But he drew his sword and squared his shoulders, stoic as always. Arthur glanced their way in surprise. He had planned on going alone. Indeed, he wasn't sure how many people Merlin's magic could protect on the other side of the wall. But he could not deny the comfort that rose at the thought of having a few warriors with him. He nodded grimly and walked forward as the portcullis was raised.

There were whispers and exclamations all through the crowd, from simple peasants to knights and nobles. It was another fine time for a grand speech. Arthur figured he probably owed them something, in case he was walking to his death. But if he failed, Camelot would fall soon after, and there were no words to soften that blow. Right now they didn't need his words; they needed his sword, his breath, his blood. And they would have it.

He took a deep breath and walked into the dark.


	9. Harrowing

Though the light preceded them, holding the darkness back as a dam constrains a river, it took all of their courage to step onto that shadowy path. It wasn't just that they couldn't see; there was something about the places the light didn't touch, an empty hunger that pulled like a strong current. They should have been in the streets of Camelot, cobbles beneath their feet and gabled buildings rising on either side. Instead, there was nothing. As though the darkness was a place all its own.

Arthur felt more than battle lust skittering down his limbs and quickening the pace of his heart. The strangeness of it slowed his stride to a mere shuffle as he made his way forward. A heavy curtain of fear lay across the path, making every inch an effort. He was walking off a cliff with every step: primal, unknowable terror. He could hear Gwaine and Leon panting behind him, echoing his own labored breaths.

"That light," Leon began, as though he simply couldn't stand the silence any longer.

"Merlin," Arthur replied with conviction.

"Well, at least someone knows what the bloody hell is going on." Gwaine squared his shoulders to move on. Arthur didn't think it was a coincidence that the blue-white orb began to brighten and dim in an urgent pattern, edging into the black as though to prod them forward. He forced himself to step forward more quickly, practically racing into the dark and unknown.

It was difficult to say whether they'd made any progress. They could have been walking in circles for all Arthur could tell, walking through shadows that could contain anything. Every step carried the precipitous sensation that some horror was about to spring out at them, but the attack never came. Everything was silent, still, empty. Nothing.

After a time, the light that led them fell on a jagged stone altar, worked with bas-reliefs that seemed to skitter away as the eye tried to catch them. The patterns were chaotic, but they were clearly intentional, even if they seemed composed of sharp angles and distorted shapes. The thick, dark blood of a fatal wound adorned the top and sides, finding grooves in the chiseled stone that seemed made for that purpose. Stretched across the top of the thing was Morgana, her eyes open but apparently unseeing. She could have been resting; her limbs were slack and lay close to her body. But her head was thrown back, mouth open in what could have been the beginnings of a scream. There were no marks on her to explain the blood, but there were crimson tendrils extending from the stone beneath her, creeping over her limbs like ivy. Where her fingers touched the stone surface, they seemed to dip into the altar like melted wax.

The weight of the darkness increased, and Arthur grunted as it shoved him to his knees. Merlin's light guttered to a fragile sheen of blue between the knights and the presence that waited on the other side, a malevolence that hungered and despised nothing more than its own hunger. The king struggled to one knee and strained to move forward, hearing his men doing the same. They were almost close enough to reach out and touch the altar, but it might as well have been miles distant with the darkness weighting their limbs. The magic limning Arthur's armor began to slip across it and pool along the length of his sword. The arm holding the weapon suddenly seemed lighter, as though the brighter light of the blade could cut through the gloom. But around the rest of his limbs, where the magic had faded, he felt the blackness crushing like a vice. He tried to speak, to give the order that might save his life, but found his tongue immovable.

Yet no order was necessary. To either side, Gwaine and Leon stepped forward to shield him with their own bodies, angled shoulder-to-shoulder. Even so, he felt like he was trying to crawl out from under the weight of his own castle, his ribs too constricted even to draw breath. His vision began to fade and flicker as he lungs screamed for release and the pain in his chest crescendoed until he was sure his ribs had finally snapped. He pushed on, refusing to cede his city, his kingdom, his people.

Arthur knew instinctively what was required. Morgana was the cause of all this, and Merlin had led him here to rip out the heart of the darkness. But his sister's eyes, trapped and aware and screaming with fear and agony, stopped him where magic could not. For a moment, he was overwhelmed by the machinations of sorcerers, by the feeling that he was little more than a pawn in their hands, a pretend king batted back and forth like a mouse between cats. Destroying an enemy in battle was one thing, but skewering his helpless sister? How could he know this was right? How could he know anything? Sorcery could make up seem sideways and murder feel like swatting a fly.

He would have faltered then, at the last, and doomed his kingdom, except that he could feel Merlin in the feeble light that clung to his blade. The magic _was_ Merlin, and it hesitated as Arthur did. It grieved for the lady who had shown a lowly serving boy some kindness, just as Arthur grieved for the princess who had taught him to stand up to the king. It failed to guide Arthur's hand, wavering in a wash of horror and terror that was all too characteristic of his softhearted servant.

And so Arthur trusted. In the face of betrayal, with his eyes open and his heart exposed. He leaped, pulling Merlin's magic forward and driving it down through his sister's chest, shattering the altar of stone with a single strike of his sword.

It was Beltane, the first day of summer's fire. And the annals would record that the sun touched the earth of Camelot that day, and it shivered to pieces in her streets.


	10. The Final Stroke

The first sensation was whiteness. He felt curiously numb, except for the twin spikes of blinding agony drilling into his skull. He managed to open his eyes and the whiteness remained, making him blink sluggishly.

 _ **ARTHUR**_

When his vision didn't clear, he tried listening, but his ears were filled with a high-pitched whine. The noise stabbed viciously, relentless and incomprehensible. For a moment, he felt like he was falling.

 _ **ARTHUR**_

It took him a moment to find his arms and legs, to realize they were connected to his body. He flopped helplessly a few times before he realized he was lying in the street, his face pressed to the cobblestones. He set his palms against the stone and started pushing himself to his feet.

 _ **ARTHUR, RUN**_

He still could hear nothing, but somehow the words crashed in his head, thunderous and compelling. Before he could begin to realize whose words they must be – _Merlin's –_ he was already moving, stumbling upright and taking shaky steps. The white finally started to bleed away and he could see the huddled forms of his knights motionless on the ground. He pulled them up one by one, enjoining them to flight without knowing what exactly they were fleeing _from._ When his vision had cleared enough to make out more than vague shapes, he glanced back.

The darkness had been diminished, but not destroyed. A heaving, rotting remnant towered over a circle of flattened buildings that extended for blocks in every direction. It looked like a distorted chimera composed of every loathsome creature that slithered or crawled. There was no body to speak of, just...piles of parts. Eyes and appendages stuck out in random directions, and a sulfurous smoke billowed from its gelatinous hide.

Despite its disorganized appearance, the gruesome thing still had some fight left in it. It was vomiting dark flame and cracking the stones of the street as it strove against the tiny ragged figure that had appeared between it and the knights. Merlin's hand was thrust upward in a gesture of denial, and the creature's strikes were exploding against some invisible barrier, outlining it periodically in blue-white sparks and molten rock. Arthur thrust aside the compulsion to flee and readied his sword.

Then Merlin looked at him.

It was a brief glance, but the veil between them had fallen away. His servant's eyes were lit with gold, and magic powerful enough to pulverize granite was cascading around him in a blinding corona. For years, Merlin had been disobeying Arthur's direct orders, putting himself in harm's way and somehow ( _magically_ ) managing to scrape by without injury. Now it was Arthur who was being ordered off the battlefield.

It could only have been a moment or two, but it felt like an eternity he spent standing there, torn between helping his friend and making the sane choice to retreat from an enemy he could not hope to defeat. It was Merlin who had taught him the limits of his station. Merlin who had showed him that there is more to leadership than giving orders. Merlin who had shown him the honor in disobedience. It would be fitting to apply those lessons now, to stand _with_ his servant rather than hide behind him.

 _ **ARTHUR, PLEASE.**_

The king relented, turning his back and driving his men back to the citadel. Even Gwaine was too disoriented to protest – or perhaps he understood Arthur's painful choice to trust Merlin's judgment. Ignoring orders when you were secretly capable of slinging lightning bolts like skipping stones was one thing, but Arthur had only his sword arm to lend to Merlin's aid, and that might be more a hindrance than a help.

So they ran. The castle was untouched, preserved by whatever spell Merlin had laid upon it. But the devastation ran right up against the walls, piling them with debris. The knights stumbled and slid over the wreckage, reaching the postern gate just as it was flung open by the knights inside.

"Sire?" The ringing in his ears had finally abated, enough that he could hear Percival's bewilderment, but his voice still sounded murky and submerged.

"Archers," Arthur replied breathlessly. He gestured upward and then began the exhausting sprint to the battlements. He heard Percival questioning Leon, and then their voices were lost in the babble of refugees and soldiers crammed into the courtyard and lining the walls. He slammed against the crenelations, which jarred his ribs. But he was panting as much with excitement as exhaustion, and the pain barely registered. A few heartbeats later, Gwaine joined him. All along the battlement, archers were positioning themselves in orderly rows.

With the destruction of the homes and shops and warehouses that lay below the citadel, the entire garrison had an unobstructed view of the nightmarish creature as it faced off against its tiny adversary. Any hopes Arthur had of keeping Merlin's identity a secret were dashed when he heard some of the crossbowmen babbling excitedly about the servant's headlong dash from the castle as soon as the darkness receded. The king put it from his mind, resolving to focus on the battle for now and give Merlin what aid he could.

With the knights clear, Merlin's defenses dwindled, and he began striking back. The creature was forced to backpedal as Merlin hammered it with blue fire. It ceased its attacks and turned its efforts to its own maladroit body, reshaping its limbs even as Merlin's magic threatened to blast them off. A sleek core lengthened amid the grotesque anatomy, corded muscles taking the place of lumps of flesh. Four cat-like legs stabilized it, and a hideous, gaping maw consolidated most of its teeth. Dozens of tentacles whipped around its flanks, some tipped with razor claws, others with mouths or even eyes.

Merlin began walking steadily backwards, angling away from the citadel and finally giving the archers a clear shot. Arthur gave the order, and hails of arrows rained down on the beast's hindquarters, slowing it enough to give Merlin time to scramble over the heaps of broken beams and shattered masonry. Merlin's retreat did not inspire confidence, and for a few moments, Arthur feared that retiring from the field had been the wrong decision. Yet there was no panic in his servant's movements – nothing that was out of the ordinary for Merlin, at any rate. Arthur began to recognize the precision of his maneuverings, if not his ultimate goal. So he carefully timed his volleys, supporting Merlin's efforts in the only way he could, wondering all the while where this was leading, and hating that he had to rely on his servant's knowledge and experience rather than his own.

The battle went on for interminable minutes, ranging so far across the city that Arthur found himself perched on the easternmost extremity of the castle. Merlin stood against the eastern wall, a sheer drop on the other side and the beast before him. As the next volley went singing through the darkness, Merlin swept to one knee. His hand brushed the earth and the stones shivered. The wall exploded outward, sending enormous chunks of masonry over the edge.

The fight below took on new viciousness, an inevitable result of the close quarters. The tentacled feline shape darted back and forth with dizzying speed for something so large. Thunder and fire met its strikes, shearing off appendages that grew back as quickly as they were destroyed. Finally, the thing lunged too far and too fast, slipping over the crumbling edge.

Was that Merlin's plan? To trick the creature into leaping out over the hundred-foot drop? For a moment, it looked as though it would work, but huge wing-like shapes flowed out from the thing's shoulders while other limbs shot backward to grip the solid stone of the castle's foundation. It teetered over the abyss but did not fall.

"Where's Merlin?" Gwaine's voice was little more than a ragged whisper, but it echoed Arthur's panicked heartbeat perfectly. The king scanned the rubble frantically, but there was no sign of the tiny figure that had been standing on the brink, goading the monster to strike.

Merlin was gone, and the loathsome creature Morgana had summoned was turning baleful eyes on Camelot.


End file.
